The prior art contains numerous examples of tool holders wherein a tool is capable of being coupled to and uncoupled from a rotary spindle without necessarily stopping rotation of the spindle. Tool holders of the general class with which the invention is adapted for use are disclosed in Nickless U.S. Pat. No. 2,719,722; King et al. U.S. Pat. No. 3,663,028; Koch U.S. Pat. No. 3,829,109; and Botimer U.S. Pat. No. 3,512,793.
One of the disadvantages of changing tools supported in rotating tool holders of the known kind is that the changing of a tool necessiates manual gripping by the operator of some part of the rotating members. It thus is possible for the operator to be injured.
Another disadvantage of known tool holders is that the tool that is to be coupled to a rotating spindle is required to be supported as it is introduced to the spindle cavity, and such support usually is accomplished manually. Unless the tool is perfectly aligned coaxially with the spindle as the tool is introduced into the spindle cavity the tool may be subjected to a whipping action, thereby again exposing the operator to the possibility to injury.
In those tool holders wherein the rotary spindle is slowed or stopped prior to coupling or uncoupling of a tool to or from the spindle, it is customary to provide a spindle braking mechanism which not only represents an additional initial expense, but also requires servicing and maintenance.
An object of the present invention is to provide a support for a tool which enables the latter to be coupled to and uncoupled from a rotary spindle without necessitating slowing or stopping of the latter and which avoids the necessity of an operator's manually engaging either the tool or the spindle.